Dysgerminoma with syncytiotrophoblastic giant cells. A histologically and clinically distinctive subtype of dysgerminoma.

The clinical and pathological features of six dysgerminomas containing syncytiotrophoblastic giant cells were studied; these represented 3% of the dysgerminomas in the AFIP files. Syncytiotrophoblastic giant cells, the distinguishing histological feature, were present either in clusters or were distributed diffusely. Human chorionic gonadotropin was demonstrated immunocytochemically within the cytoplasm of the syncytiotrophoblastic giant cells in both of the two tumors tested for it. Serum or urine gonadotropin titers, measured in four patients, were elevated in three, and two of these were thought to have ectopic pregnancies. All of the dysgerminomas were Stage Ia, and the six patients were well 1-14 years after treatment.